Question: What is the pressure of helium if it has a refractive index of 1.00004?
Paraphrase: If Helium's refractive index is 1.00004, what is the pressure?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q560 p:P1109 ?s . ?s ps:P1109 ?x filter(contains(?x , '1.00004')) . ?s pq:P2077 ?value}